/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */
package org.apache.http.util;

import java.lang.reflect.Method;

/**
 * The home for utility methods that handle various exception-related tasks.
 * 
 * 
 * @since 4.0
 */
public final class ExceptionUtils {

	/**
	 * A reference to Throwable's initCause method, or null if it's not there in
	 * this JVM
	 */
	static private final Method INIT_CAUSE_METHOD = getInitCauseMethod();

	/**
	 * Returns a <code>Method<code> allowing access to
	 * {@link Throwable#initCause(Throwable) initCause} method of {@link Throwable},
	 * or <code>null</code> if the method does not exist.
	 * 
	 * @return A <code>Method<code> for <code>Throwable.initCause</code>, or
	 *         <code>null</code> if unavailable.
	 */
	static private Method getInitCauseMethod() {
		try {
			@SuppressWarnings("rawtypes")
			Class[] paramsClasses = new Class[] { Throwable.class };
			return Throwable.class.getMethod("initCause", paramsClasses);
		} catch (NoSuchMethodException e) {
			return null;
		}
	}

	/**
	 * If we're running on JDK 1.4 or later, initialize the cause for the given
	 * throwable.
	 * 
	 * @param throwable
	 *            The throwable.
	 * @param cause
	 *            The cause of the throwable.
	 */
	public static void initCause(Throwable throwable, Throwable cause) {
		if (INIT_CAUSE_METHOD != null) {
			try {
				INIT_CAUSE_METHOD.invoke(throwable, new Object[] { cause });
			} catch (Exception e) {
				// Well, with no logging, the only option is to munch the
				// exception
			}
		}
	}

	private ExceptionUtils() {
	}

}
